In a wireless communication system, a mobile station (MS) may operate in different operation modes. For example, in a wireless communication system based on the IEEE 802.16 family of standards or the Long Term Evolution (LTE) standard, when an MS is connected with a base station (BS), the MS may operate in an active mode in which the MS stays awake all the time for communicating with the BS, or operate in a sleep mode in which the MS periodically wakes up for occasional data traffic, or operate in a client cooperation mode in which the MS operates as a relay node for relaying data from the BS to another MS. When the MS is disconnected from the BS, the MS may operate in an idle mode in which the MS is periodically paged by a paging controller in the communication system, or operate in a deregistration with content retention (DCR) mode in which information regarding the MS is retained in an access service network (ASN) gateway in the communication system.
The MS may change its operation mode according to a communication traffic condition between the MS and the BS, to save power. For example, if the MS needs to occasionally transmit data to, or receive data from, the BS, the MS may change its operation mode from the active mode to the sleep mode. Also for example, the MS may further change its operation mode to the idle mode, if the MS does not need to transmit data to, or receive data from, the BS for a relatively long time period. Traditionally, the MS initiates an operation mode transition for itself.
FIG. 1 illustrates a traditional method 100 for an MS 102 to perform an operation mode transition, where the MS 102 initiates the operation mode transition for itself. Referring to FIG. 1, the MS 102 may currently operate in the active mode, but determines that it only needs to occasionally transmit data to, or receive data from, a BS 104. Therefore, the MS 102 sends a request to the BS 104, requesting a transition to the sleep mode (112). The BS 104 receives the request from the MS 102, and sends a response to the MS 102, indicating that the MS 102 may change its operation mode to the sleep mode (114). The MS 102 may then send an acknowledgement to the BS 104 and change its operation mode to the sleep mode (116).
In reality, when a plurality of MSs in the communication system each use the method 100 to perform an operation mode transition, there may be unsuccessful attempts from the MSs since each MS is not aware of the downlink traffic to be scheduled for the MS. These unsuccessful attempts may result in undesirable signaling overhead. In addition, different designs for the MSs may raise an unfairness issue.
FIG. 2 illustrates a traditional format of a media access control (MAC) management message 200 transmitted between a BS and an MS. For example, referring to FIG. 2, the MS may include control information in a data payload 208 of the MAC management message 200 and sends the MAC management message 200 to the BS. The MAC management message 200 may include a header which further includes a flow identifier (FID) 202, an extended header (EH) indicator 204, and a length indicator 206, and the data payload 208. For example, the FID 202 may have 4 bits and indicate a connection between the BS and the MS. Also for example, the EH indicator 204 may have 1 bit, and the length indicator 206 may have 11 bits and indicate a length of the data payload 208.